This `tbc`

data set is a random subset of persons from a much larger
collection of data from the Terneuzen Birth Cohort. The total cohort
comprises of 2604 unique persons, whereas the subset in `tbc`

covers 306
persons. The `tbc.target`

is an auxiliary data set containing two
outcomes at adult age. For more details, see De Kroon et al (2008, 2010,
2011). The imputation methodology is explained in Chapter 9 of Van Buuren
(2012).